The bonding or securing of terminals is a problem that exists in the manufacture of machine insertable circuit modules known as DIP's (Dual In-Line Packages). In these packaged devices the circuit components are included in a small plastic box, and it is necessary to provide external leads that are bonded to the internal boxed circuits. Further, in the design of modern day circuitry there are needs for small box packed, passive components such as capacitors and resistors which are machine insertable and bondable to printed circuit boards. Again in the manufacture of these boxed discrete components, there is a problem of bonding externally extending leads to internally boxed components. In particular, the present invention contemplates providing a terminal bonding and packaging method for small rolled film capacitors or other discrete electrical devices in such a manner as to provide packaged devices which are readily machine insertable in printed circuit boards.
In the assembly of these types of electrical components or modules, it is necessary to attach lead wires or terminals to what may be termed a component blank so that the attachment is made with a minimum amount of series resistance being introduced at the attachment sites. If a significant series resistance is introduced at the bonding site, then a terminated component may be unsuitable for use in utilization circuits having critical electrical requirements. One of the causes of introduction of excessive series resistance resides in not providing sufficient force to terminal leads during the bonding of the leads to the component which results in the formation of defective bonds. Further, if insufficient force is applied to the terminal leads during bonding, a defective bond may not be easily detected following manufacture but may result in terminal lead separation or the introduction of added resistance due to degradation of the bonded interface during subsequent use of the terminated component in a utilization circuit. The problem is further complicated when the lead attachment must be effected within a very small box containing the component to be terminated.
Lead terminal bonding is recognized as a continuing problem and many different methods have been devised in attempts to secure good bonds of terminals to components such as rolled metallized film capacitors. In particular, many diverse types of termination methods and terminal structural arrangements have been developed to terminate rolled metallized film capacitors. As an example, U.S. Pat. No. 2,531,185 to J. H. Wurster discloses the use of conductive strips as terminations of rolled film type capacitors wherein the conductive strips are laid to engage exposed portions of the metallized capacitor plates, and then are held in place by a strap of insulating material wrapped around the capacitor. In U.S. Pat. No. 3,906,297 to D. E. Hunt there is illustrated a terminal construction for rolled film capacitors wherein feet sections of "L" shaped lead wires are bonded to metal or solder end electrodes formed on the ends of the rolled film capacitor blanks. Moreover, during termination of rolled film capacitors of this general type, such as disclosed in U.S. Pat. No. 3,939,440 to Berg et al., it is the common practice to grip a pair of terminals, and advance the gripped terminals into forcible engagement with heat fusible metallic electrodes formed on opposite ends of a capacitor blank while applying heat to bond the terminals to the capacitor blank.